On a bitterly cold December morning in 2011, we watched as the last U.S. troops crossed the border into Kuwait, ending America's war in Iraq.

More than 100 vehicles were in that convoy, snaking its way across the desert and through the floodlit border crossing, leaving behind empty bases and memories of nearly 4,500 American lives that were lost.

Americans breathed a sigh of relief. Many Iraqis held their breath. War, they feared, was far from over for them, and time has borne out their fears. The death and violence never stopped -- it's just that the bombs and bullets faded from American minds and television screens once the pull-out was complete.

Two years later we're back in Iraq and things are in many ways worse for Iraqis than when the Americans left.

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Photos:Scenes from Iraq

Photos:Scenes from Iraq

Scenes from Iraq – In this image taken on January 15, a woman walks through central Baghdad, Iraq, crossing a bridge over the Tigris River. CNN's Michael Holmes is in the Iraqi capital for the first time in two years. Click through to see images from Holmes and CNN producer Hamdi Alkhshali.

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Photos:Scenes from Iraq

Scenes from Iraq – Former interim Prime Minister Ayad Allawi, seen here in an interview with Holmes, became Iraq's first head of government following the overthrow of the Saddam Hussein regime. Allawi spoke to CNN about the current government and the sectarian violence among ethnic and religious groups in Iraq.

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Photos:Scenes from Iraq

Scenes from Iraq – Holmes says traffic jams are a way of life in Baghdad. Just moving around the city is an exercise in moving from one checkpoint to the next.

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Photos:Scenes from Iraq

Scenes from Iraq – Holmes says getting around the city is as difficult as ever, but despite the checkpoints, the violence in Baghdad is as bad as it's been in years.

Scenes from Iraq – CNN's Hamdi Alkhshali says the pole of Saddam Hussein's famous statue is still standing 11 years after the U.S. invasion in 2003.

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Photos:100 moments from the Iraq War

Photos:100 moments from the Iraq War

U.S. Marines in northern Kuwait gear up after receiving orders to cross the Iraqi border on March 20, 2003. It has been more than 10 years since the American-led invasion of Iraq that toppled the regime of Saddam Hussein. Look back at 100 moments from the war and the legacy it left behind.

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Photos:100 moments from the Iraq War

A pedestrian looks at front-page headlines on display outside the future site of the Newseum in Washington on March 20, 2003.

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Photos:100 moments from the Iraq War

Smoke and flames rise from the riverside presidential palace compound in Baghdad after a massive airstrike on March 21, 2003.

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Photos:100 moments from the Iraq War

President George W. Bush meets with his war council in the Situation Room of the White House on March 21, 2003. Clockwise from foreground: National Security Adviser Condoleezza Rice, CIA Director George Tenet, Chief of Staff Andy Card, Secretary of State Colin Powell, Secretary of Defense Donald Rumsfeld and Chairman of the Joint Chiefs of Staff Gen. Richard Myers were present.

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Photos:100 moments from the Iraq War

A U.S. Marine from Task Force Tarawa engages Iraqi forces from an armored assault vehicle on March 23, 2003, in the southern city of Nasiriyah.

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Photos:100 moments from the Iraq War

Marines walk single-file through the desolate landscape in Nasiriyah on March 26, 2003. As night falls on the city, the troops are on alert for a counterattack.

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Photos:100 moments from the Iraq War

A night-vision image shows U.S. military personnel carrying Pfc. Jessica Lynch off a helicopter on April 1, 2003, at an undisclosed location in Iraq. She had been missing since March 23, when she and members of her unit were ambushed by Iraqi forces.

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Photos:100 moments from the Iraq War

Members of the 3rd Battalion, 4th Marines, storm Diyala Bridge in Baghdad on April 7, 2003.

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Photos:100 moments from the Iraq War

Marines pull down a statue of Saddam Hussein, a symbolic finale to the fall of Baghdad, on April 9, 2003.

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Photos:100 moments from the Iraq War

Iraqis flee Baghdad on April 11, 2003, as the capital city descended into chaos with widespread looting and lawlessness.

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Photos:100 moments from the Iraq War

Marines hold a memorial service for friends killed in a battle weeks earlier on April 13, 2003, near Al-Kut, Iraq.

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Photos:100 moments from the Iraq War

Iraqi National Museum Deputy Director Mushin Hasan sits among destroyed artifacts on April 13, 2003, in Bagdhad. The museum was severely looted.

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Photos:100 moments from the Iraq War

Iraqi men push the head of a statue of Saddam Hussein after its destruction on April 18, 2003, in Baghdad.

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Photos:100 moments from the Iraq War

Dressed in a flight suit, President Bush meets pilots and crew members of the aircraft carrier USS Abraham Lincoln who were returning to the United States on May 1, 2003, after being deployed in the Gulf region.

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Photos:100 moments from the Iraq War

Sailors applaud as President Bush addresses the nation aboard the USS Abraham Lincoln on May 1, 2003. Standing beneath a banner that read "Mission Accomplished," the president declared major fighting over in Iraq and called it a victory in the ongoing war on terrorism.

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Photos:100 moments from the Iraq War

A U.S. Marine pulls down a picture of Saddam Hussein at a school in Al-Kut on April 16, 2003.

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Iraqi men check a list near the remains of bodies excavated from a mass grave on the outskirts of Al Musayyib on May 31, 2003. Locals said they uncovered the remains of hundreds of Shiite Muslims allegedly executed by Saddam Hussein's regime after their uprising following the 1991 Gulf War.

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U.S. Army 101st Airborne troops investigate a house where Saddam Hussein's sons Uday and Qusay were killed in Mosul, Iraq, on July 23, 2003. The house, in an affluent neighborhood, was the scene of a fierce gunbattle.

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Photos:100 moments from the Iraq War

Army Cpl. Curtis Laymon of the 101st Airborne Rakkasan regiment is reflected in a pool of oil from the Iraqi-Turkey pipeline in Iraq's Ninewa province on October 29, 2003. The pipeline was blown apart by saboteurs two weeks earlier.

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Photos:100 moments from the Iraq War

An Iraqi police lieutenant's stars lie in a puddle of blood after a car bombing that targeted a police station in Baquba on November 22, 2003.

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A construction worker removes debris from a destroyed building in Baghdad on December 11, 2003.

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Photos:100 moments from the Iraq War

Saddam Hussein's picture is taken December 14, 2003, after his capture a day earlier. U.S. troops found Hussein hiding near his hometown of Tikrit.

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Photos:100 moments from the Iraq War

The entrance to the "spider hole" where Saddam Hussein was hiding in Ad Dawr is seen from the inside on December 15, 2003.

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Photos:100 moments from the Iraq War

A bound Iraqi informer, with his name inked in English across his back, crouches beside soldiers in the 4th Infantry Division after providing outdated information during a morning raid in in Samarra on December 19, 2003.

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Photos:100 moments from the Iraq War

Eman Mohammed, 7, stands in the Kurdish refugee camp in Kirkuk on January 7, 2004. Since 2003, thousands of internally displaced Kurds have returned to Kirkuk.

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Photos:100 moments from the Iraq War

Laborers work on a hotel in Baghdad on January 15, 2004.

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Photos:100 moments from the Iraq War

A worker turns a valve at the Shirawa oil field outside the northern city of Kirkuk on January 19, 2004. The security of Iraq's oil infrastructure had improved, but exports through the region's main pipeline had yet to resume.

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Photos:100 moments from the Iraq War

A boy stands at the scene of a car bombing in front of the Shaheen Hotel in Baghdad on January 28, 2004.

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Photos:100 moments from the Iraq War

Mourners carry coffins in Karbala on March 3, 2004. A day after a series of bombs killed dozens and injured hundreds during the Ashura ceremony in the Shiite holy city of Karbala, Shiite Muslims began burying their dead.

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Photos:100 moments from the Iraq War

Iraqi insurgents wave their national flag as they celebrate in front of a burning U.S. military tanker they hit with rocket-propelled grenade on April 9, 2004. The attack took place on the road from Baghdad to Fallujah.

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Photos:100 moments from the Iraq War

Photographs depicting detainee abuse inside Abu Ghraib prison at the hands of U.S. troops were released in late April 2004. The fallout was immediate, and the images gave anti-war protesters ammunition to rally people to their cause.

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Photos:100 moments from the Iraq War

Iraqis look at rows of graves at an overflowing cemetery built in a soccer arena in Fallujah on May 3, 2004.

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At home in Baghdad with his new prosthetic leg, Ahsan Hameed, 20, sits while his aunt looks it over on July 17, 2004. He lost his left leg above the knee to a stray bullet in April.

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Photos:100 moments from the Iraq War

Construction workers weld beams at the Ministry of Transportation building in Baghdad on July 21, 2004. The building was being rebuilt after it was gutted by a fire.

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Photos:100 moments from the Iraq War

Iraqi national guardsman Ridha Abdulkarim lies in a hospital bed after a car bomb detonated at a checkpoint in Baquba on August 3, 2004. The bomb killed six guardsmen and wounded six others, Iraqi authorities said.

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Photos:100 moments from the Iraq War

Shiite militia members prepare to fire during clashes with U.S. forces in Najaf on August 7, 2004. It was the third day of continuous fighting in the holy city.

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An Iraqi militia member injured in a U.S. airstrike in Najaf is assisted by one of his comrades on August 24, 2004. They were walking past the shrine of Imam Ali to make their way to a militia hospital.

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Photos:100 moments from the Iraq War

Iraqi Shiite faithful gather in Najaf on August 27, 2004, to mark the end of a battle. Rebel leader Muqtada al-Sadr ordered his fighters to lay down their arms in a peace deal brokered by Iraq's most revered Shiite cleric, Grand Ayatollah Ali al-Sistani.

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Anti-war protesters in New York carry mock coffins draped with U.S. flags on August 29, 2004. Thousands took part in demonstrations outside Madison Square Garden on the eve of the Republican National Convention.

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Photos:100 moments from the Iraq War

Members of the Iraqi Intervention Forces listen to last-minute instructions before heading out with U.S. troops to begin a major offensive on the insurgent stronghold of Fallujah on November 8, 2004.

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Photos:100 moments from the Iraq War

Marines search houses in Fallujah for insurgents on November 10, 2004.

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Marines rest and check a map in a house during an offensive in Fallujah on November 11, 2004.

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Iraqi men are arrested during a house raid in Fallujah on November 13, 2004.

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Marines take position on a roof in the restive city of Fallujah on November 13, 2004.

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U.S. Army medics treat a wounded Jordanian fighter in Fallujah on November 14, 2004.

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Photos:100 moments from the Iraq War

A U.S. Marine and a soldier from the New Iraqi Army process a detainee during operations in Fallujah on November 17, 2004.

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Photos:100 moments from the Iraq War

Marines use explosives to open rooftop doors while searching houses in Fallujah for insurgents on November 22, 2004.

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Photos:100 moments from the Iraq War

Marines clear a home in Fallujah after four insurgents staged a bloody counterattack, killing one American and wounding many others, on November 23, 2004.

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Photos:100 moments from the Iraq War

Spc. Franklin Smith pulls away as a mortar blast is fired from the edge of the U.S. airbase in Tal Afar on January 17, 2005. U.S. teams would frequently fire "harassment and interdiction" mortar fusillades toward suspected enemy positions.

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Photos:100 moments from the Iraq War

Iraqis look over their ballots on election day in the Sadr City neighborhood of Baghdad on January 30, 2005. It was the country's first multiparty election in half a century.

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Photos:100 moments from the Iraq War

Election officials count ballot papers at night on January 30, 2005, in the Shiite holy city of Najaf. Despite threats, thousands of men and women cast their votes.

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Photos:100 moments from the Iraq War

Army Sgt. 1st Class Troy Hawkins is tended to after getting wounded during a firefight while on patrol with an Iraqi army unit in the Haifa Street neighborhood of Baghdad on February 16, 2005. Afterward, he continued to fight in the narrow streets.

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Photos:100 moments from the Iraq War

An Iraqi soldier stands watch at a teahouse while on patrol with U.S. soldiers in Baghdad on February 23, 2005.

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Photos:100 moments from the Iraq War

President Bush shakes hands with former Sen. Charles Robb, left, and Judge Laurence Silberman during a news conference in Washington on March 31, 2005. The co-chairmen of the Iraqi Intelligence Commission issued a report indicating that U.S. intelligence agencies were wrong in most pre-war assessments about weapons of mass destruction in Iraq.

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Photos:100 moments from the Iraq War

Iraqi Shiite demonstrators loyal to cleric Muqtada al-Sadr burn a U.S. flag during a protest in Baghdad on April 9, 2005. The rally was called on the second anniversary of the fall of Baghdad, with protesters demanding an end to the U.S. military presence in Iraq.

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Photos:100 moments from the Iraq War

People gather at the scene of a car bombing near a busy market in eastern Baghdad on May, 12, 2005.

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Photos:100 moments from the Iraq War

A resident makes a phone call in the aftermath of a double suicide car bombing that struck civilians living near the blast walls that protect the Hamra Hotel in Baghdad on November 18, 2005.

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Photos:100 moments from the Iraq War

Sgt. Thomas Gaines kisses his wife during a welcome-home ceremony in Fort Stewart, Georgia, on May 11, 2006. About 280 members of the Georgia National Guard 48th Brigade returned home from a year-long deployment to Iraq.

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Photos:100 moments from the Iraq War

A British Royal Air Force gunner waves to a goat herder during a patrol of northern Basra province on July 26, 2006.

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Photos:100 moments from the Iraq War

A British armored vehicle is illuminated by traffic during a patrol of Basra on July 27, 2006.

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Photos:100 moments from the Iraq War

Ousted Iraqi leader Saddam Hussein addresses the court during his trial in the heavily fortified Green Zone of Baghdad on October 17, 2006. Hussein and six co-defendants were on trial for mass killings in the Anfal campaign against Kurdish rebels in the late 1980s.

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Photos:100 moments from the Iraq War

A Palestinian woman watches the news of Saddam Hussein's execution at her home in the West Bank town of Jenin on December 30, 2006. Hussein was hanged for his role in the 1982 Dujail massacre, in which 148 Iraqis were killed after a failed assassination attempt against the then-president.

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Photos:100 moments from the Iraq War

U.S. Marines prepare for a military operation at Camp Ramadi in Anbar province on January 14, 2007.

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Photos:100 moments from the Iraq War

American forces in Ramadi watch President Bush deliver the annual State of the Union address on January 24, 2007. The president announced plans to increase the size of the U.S. military by 92,000 troops.

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Photos:100 moments from the Iraq War

An American Apache helicopter provides air support while a Marine takes aim after being fired upon by insurgents near the Euphrates River in Ramadi on February 2, 2007.

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Iraqi children watch U.S. Army soldiers climb to the roof of their school to get a high vantage point in Baghdad on April 15, 2007.

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U.S. Marines sleep at their patrol base in the area known as Zaidon in Al Anbar province on May 12, 2007.

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Mary McHugh mourns her fiance, Sgt. James Regan, at Arlington National Cemetery in Washington on May 27, 2007. The American Special Forces soldier was killed by an IED in Iraq in February.

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Photos:100 moments from the Iraq War

U.S. soldiers and an Iraqi contractor build a concrete wall between Sunni and Shiite areas of the south Dora neighborhood of Bagdhad in the early hours of July 4, 2007.

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Photos:100 moments from the Iraq War

Iraqi army commandos teach junior soldiers during a combat training course in Baquba on July 18, 2007.

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Medics treat Army Spc. Jose Callazo after his mine-detecting vehicle hit a buried IED in Hawr Rajab on August 4, 2007.

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An American soldier prepares to search a home for illegal weapons in the Hurriyah neighborhood of Baghdad on September 9, 2007.

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Photos:100 moments from the Iraq War

Relatives help an Iraqi man at a hospital in Baghdad on September 20, 2007. He was injured when Blackwater security contractors opened fire on civilians on September 16, killing 17. The company lost its contract to guard U.S. staff in Iraq after the country's government refused to renew its operating license.

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Photos:100 moments from the Iraq War

Army Brig. Gen. Nolen V. Bivens presents an American flag to Maribel Ferrero during the funeral of her 23-year-old son, Army Pfc. Marius L. Ferrero, in Miami. He was killed by a roadside bomb while serving in Iraq.

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Photos:100 moments from the Iraq War

A U.S. soldier blindfolds an Iraqi man during a raid in Mukhisa on December 3, 2007. Seven men were detained after multiple assault rifles were found in the house.

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U.S. soldiers sit in a home damaged by fighting in Baghdad on March 11, 2008, near the five-year anniversary of the war.

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Commanding Gen. David Petraeus, center, and Ambassador Ryan Crocker testify before the Senate Armed Services Committee in Washington on April 8, 2008. In reporting on the success of the surge in Iraq, Petraeus said the number of U.S. troops in the country should not drop below 140,000.

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A U.S. soldier with 2nd Brigade, 1st Armored Division, stands on a kiln overlooking more than 150 brick factories in Narwan on July 1, 2008.

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A boy looks out from his family shelter at a Narwan brick factory on July 1, 2008.

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Democratic presidential candidate Sen. Barack Obama flies over Baghdad with Gen. David Petraeus during a tour on July 21, 2008.

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Maj. Gen. John Kelly, left, and Anbar province Gov. Maamoun Sami Rashid al-Alwani sign papers during a handover ceremony in Ramadi on September 1, 2008. The U.S. military turned over security control of Iraq's biggest province, once a stronghold of the Sunni insurgency.

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Photos:100 moments from the Iraq War

Iraqi Prime Minister Nuri al-Maliki tries to block a shoe thrown at President Bush during a news conference in Baghdad on December 14, 2008. The Iraqi journalist who threw the shoes missed the president but could be heard yelling in Arabic, "This is a farewell ... you dog!"

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Pfc. Jeremy Tomlinson, who was wounded a year before in Iraq, waits with fellow soldiers to greet returning comrades in Fort Carson, Colorado, on January 28, 2008. About 3,800 soldiers were coming home after a 15-month tour of duty.

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A poll worker helps a member of the Iraqi National Police cast his ballot in Baghdad on January 28, 2009. Polls were opened early to members of the Iraqi security services, many of whom would be working during the provincial elections.

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An Iraqi soldier searches a boy at a polling station in Baghdad on January 31, 2009. People across the country voted to fill 440 provincial council seats.

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President Barack Obama delivers an address on February 27, 2009, at the largest Marine post on the East Coast, Camp Lejeune in North Carolina. In his speech, Obama outlined plans for the gradual withdrawal of U.S. troops in Iraq.

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Iraqi army special forces patrol Baghdad's al-Fadel district on March 30, 2009. U.S.-backed Iraqi forces clashed with anti-al-Qaeda militants known as the Awakening Council, or Sahwa, after fighting erupted following the arrest of Adel Mashhadani, a Sahwa leader.

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A U.S. Air Force team carries a flag-draped transfer case containing the remains of Army Spc. Omar M. Albrak of Chicago at Dover Air Force Base in Delaware on May 12, 2009, just over a month after the U.S. government lifted its ban on media coverage of the returning war dead. Albrak was killed while serving in Iraq.

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Army Sgt. Donald Lewis from the 1st Cavalry Division is greeted by his wife, Nicole Lewis, after his brigade arrived home in Fort Hood, Texas, on November 10, 2009, after a year of deployment in Iraq.

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Secretary of Defense Robert Gates speaks with soldiers at a forward operating base in Kirkuk on December 11, 2009.

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An Iraqi woman votes in parliamentary elections in Kirkuk on March 7, 2010.

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U.S. soldiers salute during a handover ceremony of the entry points of Baghdad's Green Zone, now referred to as the International Zone, to Iraqi control inside the heavily fortified compound in Baghdad on June 1, 2010.

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A string of bullets lies across photographs of women adorning the armor of a Stryker vehicle north of Jalaulah on June 11, 2010.

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An Iraqi explosives expert gets into a special suit for bomb disposal during a training session organized by his U.S. counterparts at the Warhorse military base near the restive city of Baquba on August 17, 2010.

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Shiite worshipers pray during an Ashura commemoration ceremony at the Kadhimiya shrine in Baghdad on December 6, 2011. Ashura marks the death of Prophet Mohammed's grandson, the revered Imam Hussein.

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A technician works on a prosthetic at a factory in Baghdad on December 13, 2011. Iraqis have faced a shortage of prosthetics due to a spike in war-related injuries over the years.

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Iraqis gather at a women's art exhibition in a posh Baghdad neighborhood on December 14, 2011.

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Gen. Lloyd Austin retires the United States Forces-Iraq flag during a casing ceremony at the former Sather Air Base in Baghdad on December 15, 2011.

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Military personnel lower their heads during the flag casing ceremony in Baghdad on December 15, 2011. The ceremony officially marked the end of U.S. military operations in Iraq.

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A U.S. soldier prepares to fly out of the Sather Air Base in Baghdad on December 15, 2011. The last U.S. forces left Iraq and entered Kuwait on December 18, nearly nine years after launching a divisive war to oust Saddam Hussein.

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Driving in along what the U.S. military called "Route Irish" -- or the BIAP (Baghdad International Airport road) -- the stark concrete blast walls are now covered in murals, the median is grassed with palm trees and fountains. We were reminded this was done for the 2012 Arab League Summit in Baghdad, not for general "beautification."

More than 8,000 people were killed in Iraq in 2013, according to the U.N. estimates -- most of them innocent civilians caught up in the tempest of violence that grips their country.

The groundwork for today's problems began almost as soon as that last American convoy left in 2011. Sunni lawmakers protested the rounding up of many of their aides and security guards, and the country's vice president -- top Sunni leader Tariq al-Hashimi -- faced arrest and later fled the country.

The government of Prime Minister Nouri al-Maliki was supposed to usher in a political era of inclusion and reconciliation. His critics say those first days after the American departure were a signal of opposite intentions that have continued to this day.

The Sunni minority that had ruled Iraq via the iron fist of Saddam Hussein was at the political and social mercy of al-Maliki's Shia-dominated government. Today, they say, "inclusiveness" never materialized, Sunnis have been marginalized and resentment has festered in a divide-and-conquer political climate. As one local put it, "It's like if you're against us, you're a terrorist and we'll arrest you."

This resentment, aided by the violent government shutdown of Sunni protest camps, provided an opening for the al Qaeda-linked Islamic State of Iraq and Syria (ISIS) to move into the Sunni heartland of Anbar Province in force. Al Qaeda is a beast that feasts on discontent and in Anbar there is no shortage of sustenance.

A previous version of ISIS, the Islamic State of Iraq, comprised the core insurgents the Americans fought in those cities during the war. They have regrouped and strengthened across the border in Syria during that country's bloody conflict -- and extended their fight for a home for their brand of hard-line Islamism into Iraq.

The results have been deadly -- not just in Ramadi and Fallujah of course, but across the country, where, just like the "bad old days" of 2005-2009, bombings and killings have become pretty much daily events.

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Car bomb explodes in central Baghdad

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In 2006 the Americans convinced -- and paid -- Sunni tribal and religious leaders to fight the hardliners, with great success. But Sunni grievances never went away and some in Anbar see ISIS as comrades-in-arms against an al-Maliki government viewed as an oppressor of Sunnis. Other Sunnis see al-Maliki as the lesser of two evils -- they don't like how they're treated, but like even less the ISIS brand of hard-line, brutal "governance".

Al-Maliki has more than once termed the various fights and stand-offs in Ramadi and Fallujah as a fight against "al Qaeda", but it's not that simple.

The Sunni sense of being under the heel of a sectarian government, of being cut out of the running of their country, failing to share in growing oil revenues, has nothing to do with al Qaeda and won't evaporate once ISIS is forced from Ramadi and Fallujah.

The Americans aren't coming back to help out with boots on the ground, but they are giving other support -- offering drones, missiles, aircraft and other assistance.

But this isn't a battle to be won militarily. Sunnis -- many of whom have yet to get used to no longer running the country -- say they want to be part of the system that was meant to be "inclusive" but has, they feel, been anything but.